Marine Sponges – Molecular Biology and Biotechnology 8.3 Symbiotic Functions of Sponge-Associated Microorganisms 227
Part A | 8.3
parishii over a 5 year study period [8.134]. Ophiuroidea were also found to be consistently associated
with sponges, but the authors suggest that this relationship is species-specific between Callyspongia vaginalis and Ophiothrix lineata [8.135]. Although many
of these phyla are known parasites, their precise roles
within their sponge hosts are as yet not known. A mutualist relationship between a sponge (Halichondria
panicea) and a scallop (Chlamys varia) has, however,
been reported, where the sponge obtains increased suspended nutrients while the scallop gains protection
from predation [8.136].
8.2.4 Sponge-Specific Microorganisms
In a meta-analysis performed in 2002 of all the then
publicly available (n D 190) sponge-derived 16S rRNA
gene sequences, including 5 sponge species from different geographical regions such as the Mediterranean
Sea (France, Israel and Croatia), the Red Sea, the North
Pacific (Japan and USA), Australian waters (Davies
Reef), and from the Philippine Sea (Palau), researchers
revealed monophyletic clusters of sponge-derived sequences more closely related to each other than to
sequences of the same taxa derived from non-sponge
sources; leading to the hypothesis of sponge-specific
microbes [8.82]. That study established that 14 monophyletic sequence clusters from 7 bacterial phyla, representing 70% of all sponge-derived sequences, were
termed as sponge-specific. This term was defined to apply to groups of at least three sequences, which were (i)
recovered from different sponge species and/or from individuals of the same species from different geographic
locations, (ii) more closely related to each other than to
sequences from non-sponge sources, and (iii) clustered
together independently of the tree-building algorithm
used.
Further interrogation of this hypothesis followed
with the subsequent analysis in 2007 of 1700 sponge
derived publicly available 16S rRNA sequences, with
reports that 32% of all sponge-derived sequences from
at least 10 bacterial phyla and also from a major
archaeal lineage (Crenarchaeota) recruited to spongespecific clusters [8.7]. These sponge-specific clusters
included 100% (n D 21) of all sequences, then available, from the putatively sponge-specific candidate
phylum Poribacteria. High proportions of spongederived sequences from Chloroflexi (62%), Cyanobacteria (79%), Nitrospira (57%), and Spirochaetes (67%)
were classified as being sponge-specific. Notable proportions of sequences from Actinobacteria (38%),
Gemmatimonadetes (25%) and ˇ-/ -Proteobacteria
(34%) were assigned to sponge-specific clusters. Conversely, only 5% of Acidobacteria sequences, 9% of
Firmicutes sequences, and 0% of Bacteroidetes sequences were determined to be sponge-specific.
In a subsequent study in 2011, by which time
the number of publicly available (non-pyrosequencingderived) sponge-derived 16S rRNA sequences had risen
to 7500, Simister and colleagues found that 27% of
sponge-derived sequences could be assigned to spongespecific clusters from 14 bacterial phyla and one major
archaeal lineage (Thaumarchaeota) [8.117]. Similar to
previous findings, large proportions of sponge-derived
Chloroflexi (61%), Cyanobacteria (53%), Nitrospirae
(39%), and Spirochaetes (92%) were classified as being sponge-specific. While this study analyzed a dataset
of 7500 sponge-derived sequences, it like the previous study, only considered relatively long sequencing
reads. However, with the emergence of pyrosequencing 700 000 sponge-derived 16S rRNA sequences
are currently available in public databases, with reads
varying in length from 5060 bp [8.119] up to an
average 430 bp [8.120]. Recent reports which have analyzed > 110 000 sponge-derived sequences derived
by pyrosequencing, assigned between 3665% of sequences from sponge individuals to previously described sponge-specific clusters [8.118].
8.3 Symbiotic Functions of Sponge-Associated Microorganisms
While the diversity and abundance of microbes found
associated with sponges is well established, little experimental evidence exists to elucidate the symbiotic roles
of those microbes in the sponge hosts. Instead, indirect
evidence is used to support the hypotheses of commensal, mutualistic, or parasitic activities in the sponge
holobiont.
8.3.1 Molecular Methods to Elucidate
Sponge Symbiont Functions
The detection of microbial biomarker gene sequences
from sponge metagenomes has led to speculation about
possible symbiotic functional roles for those taxa.
While known physiological functions of microbes may
Part A | 8.3
parishii over a 5 year study period [8.134]. Ophiuroidea were also found to be consistently associated
with sponges, but the authors suggest that this relationship is species-specific between Callyspongia vaginalis and Ophiothrix lineata [8.135]. Although many
of these phyla are known parasites, their precise roles
within their sponge hosts are as yet not known. A mutualist relationship between a sponge (Halichondria
panicea) and a scallop (Chlamys varia) has, however,
been reported, where the sponge obtains increased suspended nutrients while the scallop gains protection
from predation [8.136].
8.2.4 Sponge-Specific Microorganisms
In a meta-analysis performed in 2002 of all the then
publicly available (n D 190) sponge-derived 16S rRNA
gene sequences, including 5 sponge species from different geographical regions such as the Mediterranean
Sea (France, Israel and Croatia), the Red Sea, the North
Pacific (Japan and USA), Australian waters (Davies
Reef), and from the Philippine Sea (Palau), researchers
revealed monophyletic clusters of sponge-derived sequences more closely related to each other than to
sequences of the same taxa derived from non-sponge
sources; leading to the hypothesis of sponge-specific
microbes [8.82]. That study established that 14 monophyletic sequence clusters from 7 bacterial phyla, representing 70% of all sponge-derived sequences, were
termed as sponge-specific. This term was defined to apply to groups of at least three sequences, which were (i)
recovered from different sponge species and/or from individuals of the same species from different geographic
locations, (ii) more closely related to each other than to
sequences from non-sponge sources, and (iii) clustered
together independently of the tree-building algorithm
used.
Further interrogation of this hypothesis followed
with the subsequent analysis in 2007 of 1700 sponge
derived publicly available 16S rRNA sequences, with
reports that 32% of all sponge-derived sequences from
at least 10 bacterial phyla and also from a major
archaeal lineage (Crenarchaeota) recruited to spongespecific clusters [8.7]. These sponge-specific clusters
included 100% (n D 21) of all sequences, then available, from the putatively sponge-specific candidate
phylum Poribacteria. High proportions of spongederived sequences from Chloroflexi (62%), Cyanobacteria (79%), Nitrospira (57%), and Spirochaetes (67%)
were classified as being sponge-specific. Notable proportions of sequences from Actinobacteria (38%),
Gemmatimonadetes (25%) and ˇ-/ -Proteobacteria
(34%) were assigned to sponge-specific clusters. Conversely, only 5% of Acidobacteria sequences, 9% of
Firmicutes sequences, and 0% of Bacteroidetes sequences were determined to be sponge-specific.
In a subsequent study in 2011, by which time
the number of publicly available (non-pyrosequencingderived) sponge-derived 16S rRNA sequences had risen
to 7500, Simister and colleagues found that 27% of
sponge-derived sequences could be assigned to spongespecific clusters from 14 bacterial phyla and one major
archaeal lineage (Thaumarchaeota) [8.117]. Similar to
previous findings, large proportions of sponge-derived
Chloroflexi (61%), Cyanobacteria (53%), Nitrospirae
(39%), and Spirochaetes (92%) were classified as being sponge-specific. While this study analyzed a dataset
of 7500 sponge-derived sequences, it like the previous study, only considered relatively long sequencing
reads. However, with the emergence of pyrosequencing 700 000 sponge-derived 16S rRNA sequences
are currently available in public databases, with reads
varying in length from 5060 bp [8.119] up to an
average 430 bp [8.120]. Recent reports which have analyzed > 110 000 sponge-derived sequences derived
by pyrosequencing, assigned between 3665% of sequences from sponge individuals to previously described sponge-specific clusters [8.118].
8.3 Symbiotic Functions of Sponge-Associated Microorganisms
While the diversity and abundance of microbes found
associated with sponges is well established, little experimental evidence exists to elucidate the symbiotic roles
of those microbes in the sponge hosts. Instead, indirect
evidence is used to support the hypotheses of commensal, mutualistic, or parasitic activities in the sponge
holobiont.
8.3.1 Molecular Methods to Elucidate
Sponge Symbiont Functions
The detection of microbial biomarker gene sequences
from sponge metagenomes has led to speculation about
possible symbiotic functional roles for those taxa.
While known physiological functions of microbes may